BENGHAZI, Libya (Reuters) - A car exploded in the Libyan city of Benghazi on Friday, wounding a prominent tribal leader who recently helped eastern forces take control of major oil ports, security and medical officials said.

Saleh al-Ateiwish, head of the Magharba tribe, was wounded as he left a mosque in Benghazi's Sidi Frej neighborhood, the security official said.

A hospital official said Ateiwish's condition was stable, adding that three other people had been hurt in the blast.

In September, Ateiwish had appealed to a faction of Libya's Petrol Facilities Guard (PFG) to relinquish control of blockaded oil ports to Khalifa Haftar's self-styled Libyan National Army (LNA).

Tribal backing was seen as crucial for the rapid and largely bloodless takeover of the ports. Haftar's forces then handed control of the terminals to the National Oil Corporation (NOC), allowing it to reopen them and double oil production to nearly 600,000 barrels per day (bpd).

The LNA said this week that it was following media reports of a planned counter attack against the ports by rival factions.

It was not immediately clear who was behind the blast, but family members at the hospital where Ateiwish was being treated called it an assassination attempt.

It is the second car bomb in less than a week in Benghazi. On Saturday an explosion in the city center killed four people including Mohamed Bugaighis, a well-known activist and supporter of Haftar.

Haftar's forces have been waging a military campaign against Islamists and other opponents in Benghazi for the past two years. They made major gains earlier this year, securing several neighborhoods, but have not been able to bring the city under full control.

Haftar and his allies in the east have so far rejected a U.N.-backed government in Tripoli that was meant to bring stability to Libya, which splintered into warring factions after an uprising that toppled veteran leader Muammar Gaddafi five years ago.